Editor's note: This week, Environmental Health Perspectives selected this trio of studies for its 2012 "Paper of the year" award. EHP notes that the importance of the research to understanding the "alterations of cognitive function following developmental exposure to environmental chemicals." Congratulations to the study authors from all of us at PAN. We are reposting our original coverage of these studies below.

School-age children have lower IQs when their mother's are exposed to pesticides during pregnancy. This is the conclusion of 3 independent studies released today in the journal Environmental Health Perspectives.

Looking at nearly 800 children from California and New York, the studies each found that maternal exposure to certain common pesticides during pregnancy predicts lower IQ, poorer working memory and perceptual reasoning. In other words, kids exposed to low levels of pesticides in utero face significant cognitive impairment later in life.

Today's studies confirm in dramatic fashion a long line of research linking pesticide exposure during critical developmental windows to children's health harms:

These new findings come on the heels of last month's study showing that mice — particularly females — exposed to the pesticide chlorpyrifos in the womb were slow learners. Last year, an explosive study out of Montreal and Harvard linked exposure to organophosphate (OP) pesticides in food to increased incidence of ADHD.

Among the most acutely toxic pesticides, OP pesticides are classified by the U.S. Environmental Protection Agency as highly or moderately toxic. This common class of neurotoxic insecticides has been in use since the 1940s, when they were first developed. PAN has long been active working to restrict the use of OPs, pressing hard for the full phaseout of chlorpyrifos, which has been banned for home use for many years because of it's danger to children but is still allowed in agricultural fields. Children of farmworkers and children in agricultural areas are thus among the most exposed to OPs, but as the New York study confirms, urban children are also at risk.

This last batch of studies all used similar methods. Researchers at the University of California, Berkeley and Mount Sinai School of Medicine measured OP pesticide markers in pregnant women's urine, while investigators at Columbia University measured the OP pesticide chlorpyrifos in umbilical cord blood. Mount Sinai administered intelligence tests to children between 6 and 9 years; Berkeley and Columbia tested 7-year-old children.

The fact that the studies all documented similar reductions in cognitive function makes the findings particularly strong. “As a group, these papers add substantial weight to the evidence linking OP pesticides with adverse effects on cognitive development by simultaneously reporting consistent findings for three different groups of children,” said Environmental Health Perspectives Editor-in-Chief Hugh A. Tilson in a press release from the journal.

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tmhwll wrote:

I definitely agree as our Bees in US have been exposed to neonicotinoid pesticides since 1997 and massive bee die-offs continue throughout U.S. since the massive introduction of neonicotinoid pesticide increased in 2000 and these directly effect the neurology of insects. Bees are a huge INDICATOR SPECIES that there is SOMETHING WRONG with the environment and if bees are losing out after feeding on pollen poisoned by neonicotinoids like imidacloprid or clothianidin, I feel that there is a link to our food. I believe that we are bioaccumulating these systemic pesticides in our bodies and the evidence of a link is unfortunately being seen our children getting mental disorders. We need to ban these from USA, check out the petition I started :http://www.change.org/petitions/help-bees-ban-imidacloprid-and-other-neonicotinoid-pesticides#signatures